Generally, a slip stopper with a slip stopping function is occasionally used for floors, passageways, and stairs in building structures, floors and steps of buses, trucks and special vehicles, decks of railroad vehicles and ships, and scaffolding at construction sites. Such a slip stopper, for example, a slip stopper as shown in FIGS. 12(A)–12(C), has been conventionally known. This is a so-called striped steel plate, the steel plate has a plurality of projections 10 molded in a continuous patterned shape. A corresponding slip stopping effect can be expected in the case of normal scaffolding, however, the height of the projections 10 of this striped steel plate is low and is curved, so that a more reliable slip stopper is required for works at heights, scaffolding that is exposed to rain or mud, or when workers step on a cover covering the upper surface of a construction machine as a stepping surface during maintenance.
Therefore, as shown in FIGS. 13(A) and 13(B), a slip stopper has been provided in which slip stopping parts 12 having raised edges, formed by the marginal section of a through hole 11 stamped out into a circle shape or a star shape, are formed in a running pattern. In this slip stopper, the raised portions of the slip stopping part 12 can be made sufficiently high, and sharp shear planes are formed by means of stamping-out, so that a great slip stopping effect can be obtained.
If the slip stopper having the through hole stamped out is used as it is as, for example, for a cover to cover the upper surface of a construction machine, problems such that rainwater or dirt enters the inside of the cover, heated air from an engine blows upward from the cover, or noise escape are inevitable. Therefore, a double structure is created comprising a flat steel plate fixed to the lower side of the slip stopper to prevent the abovementioned problems. However, the double structure increases production processes and costs in comparison with the single structure, and further poses a problem in that mud or dust entering the through hole of the slip stopper accumulates between the slip stopper and the lower side flat steel plate or collects in the through hole, and makes cleaning difficult. These problems are to be solved by the invention.